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BL 8-inch Mk VIII naval gun

May 07, 2024

The BL 8 inch gun Mark VIII[note 1] was the main battery gun used on the Royal Navy's County-class cruisers,[note 2] in compliance with the Washington Naval Treaty of 1922. This treaty allowed ships of not more than 10,000 tons standard displacement and with guns no larger than 8 inches (203 mm) to be excluded from total tonnage limitations on a nation's capital ships. The 10,000 ton limit was a major factor in design decisions such as turrets and gun mountings. A similar gun formed the main battery of Spanish Canarias-class cruisers.[3] In 1930, the Royal Navy adopted the BL 6 inch Mk XXIII naval gun as the standard cruiser main battery in preference to this 8-inch gun.[4]

Ordnance BL 8 inch gun Mk VIII
Forward 8-inch turrets aboard HMAS Canberra
TypeNaval gun
Coast defence gun
Place of originUnited Kingdom
Service history
In service1927 – 1954[1]
Used byRoyal Navy
Royal Australian Navy
Spanish Navy
WarsSecond World War
Spanish Civil War
Production history
No. built168[2]
Specifications
Mass17.5 tonnes[2]
Barrel length400 inches/10 meters(50 calibres)[2]
Shell256 pounds (116 kg)
Calibre8-inch (203 mm)[2]
Muzzle velocity2805 feet per second (855 m/s)[2]
Maximum firing range28 kilometres (17 mi)[2]

Description edit

These guns, 50 calibres long, were built-up guns which consisted of a wire-wound tube encased within a second tube and jacket with a Welin breech block and hydraulic or hand-operated Asbury mechanism. Two cloth bags each containing 15 kg (33 lb) of cordite were used to fire a 116 kg (256 lb) projectile. Mark I turrets allowed gun elevation to 70 degrees to fire high-explosive shells against aircraft. Hydraulic pumps proved incapable of providing sufficient train and elevation speed to follow contemporary aircraft; so simplified version of the Mark II turrets with a maximum elevation of 50 degrees were installed in Exeter. Each gun could fire approximately five rounds per minute. Useful life expectancy was 550 effective full charges (EFC) per barrel.[2]

Naval service edit

The following ships mounted Mk VIII guns in 188-tonne twin turrets.[2] The standard main battery was four turrets, but Exeter and York carried only three to reduce weight and formed the separate York class.[5]

  • County-class heavy cruisers : 13 ships
    • Canarias-class heavy cruisers : 2 ships
  • York-class heavy cruisers : 2 ships

Coast defence guns edit

 
Gun of 428 Battery Coast Defence Artillery firing at dusk during World War II

Six single guns capable of elevating to 70 degrees were installed as coastal artillery in the Folkestone-Dover area during the Second World War.[2]

Ammunition edit

Shell trajectory edit

Range with 256 lbs. (116.1) SAPC with MV = 2,725 fps (831 mps)

Range[2] Elevation Time of flight Descent Impact velocity
5,000 yd (4,570 m) 2° 11′ 6 s 2° 31′ 2154 ft/s (657 m/s)
10,000 yd (9,140 m) 5° 14′ 14 s 7° 15′ 1683 ft/s (513 m/s)
15,000 yd (13,720 m) 9° 47′ 25 s 15° 49′ 1322 ft/s (403 m/s)
20,000 yd (18,290 m) 16° 34′ 38 s 28° 31′ 1169 ft/s (356 m/s)
25,000 yd (22,860 m) 26° 44′ 56 s 43° 7′ 1164 ft/s (355 m/s)
29,000 yd (26,520 m) 41° 28′ 79 s 56° 37′ 1240 ft/s (378 m/s)

See also edit

Weapons of comparable role, performance and era edit

Surviving examples edit

Notes edit

  1. ^ Mark VIII = Mark 8. Britain used Roman numerals to denote Marks (models) of ordnance until after World War II. Hence this was the eighth model of BL 8-inch naval gun.
  2. ^ A more accurate term is "Treaty Cruiser", as the term heavy cruiser was only formally defined at the time of the London Naval Treaty of 1930. However, all the 8-inch gun cruisers introduced as a result of the 1922 Washington Treaty were what became known as "heavy cruisers".

References edit

  1. ^ Whitley 1995 pp.17,83&89
  2. ^ a b c d e f g h i j Campbell 1985 pp.31–33
  3. ^ Campbell 1985 p.389
  4. ^ Whitley 1995 pp.96–127
  5. ^ Lenton & Colledge 1968 pp. 36–39

Bibliography edit

  • Campbell, John (1985). Naval Weapons of World War Two. Naval Institute Press. ISBN 0-87021-459-4.
  • Lenton, H.T. & Colledge, J.J. (1968). British and Dominion Warships of World War Two. Doubleday and Company.
  • Whitley, M.J. (1995). Cruisers of World War Two. Brockhampton Press. ISBN 1-86019-8740.

External links edit

 
Wikimedia Commons has media related to BL 8 inch Mk VIII naval gun.
  • Tony DiGiulian, Britain 8"/50 (20.3 cm) Mark VIII
  • Terry Gander,

May 07, 2024
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The BL 8 inch gun Mark VIII note 1 was the main battery gun used on the Royal Navy s County class cruisers note 2 in compliance with the Washington Naval Treaty of 1922 This treaty allowed ships of not more than 10 000 tons standard displacement and with guns no larger than 8 inches 203 mm to be excluded from total tonnage limitations on a nation s capital ships The 10 000 ton limit was a major factor in design decisions such as turrets and gun mountings A similar gun formed the main battery of Spanish Canarias class cruisers 3 In 1930 the Royal Navy adopted the BL 6 inch Mk XXIII naval gun as the standard cruiser main battery in preference to this 8 inch gun 4 Ordnance BL 8 inch gun Mk VIIIForward 8 inch turrets aboard HMAS CanberraTypeNaval gunCoast defence gunPlace of originUnited KingdomService historyIn service1927 1954 1 Used byRoyal Navy Royal Australian Navy Spanish NavyWarsSecond World War Spanish Civil WarProduction historyNo built168 2 SpecificationsMass17 5 tonnes 2 Barrel length400 inches 10 meters 50 calibres 2 Shell256 pounds 116 kg Calibre8 inch 203 mm 2 Muzzle velocity2805 feet per second 855 m s 2 Maximum firing range28 kilometres 17 mi 2 Contents 1 Description 2 Naval service 3 Coast defence guns 4 Ammunition 5 Shell trajectory 6 See also 6 1 Weapons of comparable role performance and era 7 Surviving examples 8 Notes 9 References 10 Bibliography 11 External linksDescription editThese guns 50 calibres long were built up guns which consisted of a wire wound tube encased within a second tube and jacket with a Welin breech block and hydraulic or hand operated Asbury mechanism Two cloth bags each containing 15 kg 33 lb of cordite were used to fire a 116 kg 256 lb projectile Mark I turrets allowed gun elevation to 70 degrees to fire high explosive shells against aircraft Hydraulic pumps proved incapable of providing sufficient train and elevation speed to follow contemporary aircraft so simplified version of the Mark II turrets with a maximum elevation of 50 degrees were installed in Exeter Each gun could fire approximately five rounds per minute Useful life expectancy was 550 effective full charges EFC per barrel 2 Naval service editThe following ships mounted Mk VIII guns in 188 tonne twin turrets 2 The standard main battery was four turrets but Exeter and York carried only three to reduce weight and formed the separate York class 5 County class heavy cruisers 13 ships Canarias class heavy cruisers 2 ships York class heavy cruisers 2 shipsCoast defence guns edit nbsp Gun of 428 Battery Coast Defence Artillery firing at dusk during World War II Six single guns capable of elevating to 70 degrees were installed as coastal artillery in the Folkestone Dover area during the Second World War 2 Ammunition edit nbsp World War II semi armour piercing shell with marker dye to identify ship that fired it for range corrections nbsp 1930s high explosive shell nbsp Coast defence gun shells World War IIShell trajectory editRange with 256 lbs 116 1 SAPC with MV 2 725 fps 831 mps Range 2 Elevation Time of flight Descent Impact velocity 5 000 yd 4 570 m 2 11 6 s 2 31 2154 ft s 657 m s 10 000 yd 9 140 m 5 14 14 s 7 15 1683 ft s 513 m s 15 000 yd 13 720 m 9 47 25 s 15 49 1322 ft s 403 m s 20 000 yd 18 290 m 16 34 38 s 28 31 1169 ft s 356 m s 25 000 yd 22 860 m 26 44 56 s 43 7 1164 ft s 355 m s 29 000 yd 26 520 m 41 28 79 s 56 37 1240 ft s 378 m s See also editWeapons of comparable role performance and era edit 203mm 50 Modele 1924 gun French equivalent 20 3 cm SK C 34 Naval gun German equivalent 203 mm 53 Italian naval gun Italian equivalent 20 cm 50 3rd Year Type naval gun Japanese equivalent 8 55 caliber gun US equivalentSurviving examples editA gun from HMAS Australia outside the Australian War Memorial CanberraNotes edit Mark VIII Mark 8 Britain used Roman numerals to denote Marks models of ordnance until after World War II Hence this was the eighth model of BL 8 inch naval gun A more accurate term is Treaty Cruiser as the term heavy cruiser was only formally defined at the time of the London Naval Treaty of 1930 However all the 8 inch gun cruisers introduced as a result of the 1922 Washington Treaty were what became known as heavy cruisers References edit Whitley 1995 pp 17 83 amp 89 a b c d e f g h i j Campbell 1985 pp 31 33 Campbell 1985 p 389 Whitley 1995 pp 96 127 Lenton amp Colledge 1968 pp 36 39Bibliography editCampbell John 1985 Naval Weapons of World War Two Naval Institute Press ISBN 0 87021 459 4 Lenton H T amp Colledge J J 1968 British and Dominion Warships of World War Two Doubleday and Company Whitley M J 1995 Cruisers of World War Two Brockhampton Press ISBN 1 86019 8740 External links edit nbsp Wikimedia Commons has media related to BL 8 inch Mk VIII naval gun Tony DiGiulian Britain 8 50 20 3 cm Mark VIII Terry Gander Twentieth century British coast defence guns Retrieved from https en wikipedia org w index php title BL 8 inch Mk VIII naval gun amp oldid 1210836180, wikipedia, wiki, book, 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